As soon as my wife left for the day this morning...

[jimtranr]

Originally Posted by Vesuvius

Jim,

I'd mount the flat-panel TV, put the turntable on the cabinet, and then finish off covering that fireplace with more tubetraps... should be WAF-acceptable since it will add more symmetry to the room.

An option I'd considered, but it poses some, er, "problems." I actually have an even more symmetrical concept in mind that'll keep me busy with my table and miter saws, plate joiner, and router for quite a while, but it will require some preparatory schmoo--well, let me put it this way. There's a cartoon in Bill Mauldin's Up Front that has either Willie or Joe parked prone in a slight depression beneath a stationary German Tiger tank somewhere in the Normandy hedgerows. He speaks in hushed tones into his walkie-talkie to divisional artillery: "I have a target for ya', but ya' gotta be patient."

[Still-One]

Originally Posted by jimtranr

I then sent photos and a diagram to Michael Adams, who looked it over and called with a suggestion to "clamp" the speakers and remove all but the fireplace, piano, and rear corner traps--the plan you see in the diagram. The result was...Woohoo!

The "clamp" is what makes it go. Despite the lack of front corner trapping, that technique effectively clears "mud" out of the presentation.

I just do not understand clamping the speakers. From everything we read you want as little of anything around your drivers including enclosures. I am not arguing that you shouldn't like the sound, I just can't understand why it works.

Jim

[Michael TubeTrap]

Originally Posted by Still-One

I just do not understand clamping the speakers. From everything we read you want as little of anything around your drivers including enclosures. I am not arguing that you shouldn't like the sound, I just can't understand why it works.

Jim

I couldn't agree with you more, Jim. Same training I had my whole life, and the reason why speakers got better sounding when their boxes stopped looking like boxes, and started looking like sculpture. Here is what we found:

First and always, your ears have to drive the adjustments. We have two famous contrary experiences on this subject in the company's memory. I'll get to technical details after.

First experience, "don't get anything near the tweeters!". We were building some custom acoustics for a speaker manufacturer. Their speakers weren't large, but they did have a small line array of tweeters down one side of the cabinet. When we set their speakers into our custom acoustics, the speakers sounded lifeless. We'd drained all the life out of the poor speakers! Turns out, this particular speaker's performance depended on the wavefront wrapping around the cabinet and pushing off. By putting sound absorption right next to the tweeters, we robbed the wavefront of the "push-off" zone, with the result the tweeters sounded attenuated. We fixed the problem by a) freaking out; b) figuring out what we had broken; and c) carving away the acoustics from around the tweeter. As you can imagine, we followed this order of events very carefully.

To completely contradict the above experience, our engineering asst and I did an experiment to see how close we could get sound panels to in-wall speakers. Our experiment involved small studio monitors, and some sleeves built from sound panels. Listening to music with a good soundstage, I closed my eyes and had Jordan slowly slide the sleeves forward on the speaker cabinets, to the point that the monitors were playing through little tiny fiberglass tunnels. It should have sounded terrible, but I heard almost no difference! If it had been a hard reflective material, the "cupping" sound would have been atrocious and the soundstage would have collapsed to two point sources. But we were putting "anti-reflection" material near the two drivers, so no reflections, no cupping, no buildup of off-axis chatter.

So much for the practical experience. Art tells us that the 4lb/cu ft fiberglass has the same impedance as the pressure front of a soundwave. When you put Tubes up next to a speaker, the wavefront that wraps around the cabinet "feels" right when it hits the Tube. It isn't compressed by greater resistance, like it would if it were placed next to a wall, and it isn't pulled apart by too much absorption, which would pull the power out of the wavefront.

On some speakers you can have the Tubes right up flush with the front of the baffle board. On other speakers you have to have the speaker's front stand proud of the Tubes, sometimes with the Tubes as much as 6" down the side of the cabinet. As someone said earlier, let your ears be in charge.

One acoustical principle that comes up in our practice time and again: if you can get close to the sound, it takes very little acoustics to control it. It takes a lot of acoustics to control sound once it has expanded out to the edges of the room. This approach lets you get close to the sound, use very little acoustics, and get great results. Try it!

Michael Adams

[jimtranr]

Originally Posted by Still-One

I just do not understand clamping the speakers. From everything we read you want as little of anything around your drivers including enclosures. I am not arguing that you shouldn't like the sound, I just can't understand why it works.

I had to get over that counterintuitive hump, too, Jim, since, as I'd explained to Michael, I'd tried the same thing with Magnepan 1.6's in an earlier system and heard "the life sucked out of them." But they're dipoles dependent in no small measure on the backwave for their "effect," and that was in a different room as well. That aside, I still had reservations based on the same "keep everything clear of the speakers" orthodoxy I'd grown up with. But it was clear less than 30 seconds into the audition with the SE-3's "clamped" that it's a technique that worked--and far beyond my expectations.

Even more persuasive, perhaps, were the immediate reactions of, first, my wife (who was blown away by the clearout of audio "mud") and then a "somewhat-audiophile" neighbor who could not get over the "I can almost step into it" soundstage of a well-recorded Gershwin Concerto in F. (Once his wife sees how that effect was achieved I doubt that she'll let him come over to play anymore.)

[Still-One]

Michael
Thanks for the thoughtful explanation as to why something so counterintuitive might work in some applications. This is one crazy hobby we are involved in.

Jim

[Still-One]

Originally Posted by jimtranr

I had to get over that counterintuitive hump, too, Jim, since, as I'd explained to Michael, I'd tried the same thing with Magnepan 1.6's in an earlier system and heard "the life sucked out of them." But they're dipoles dependent in no small measure on the backwave for their "effect," and that was in a different room as well. That aside, I still had reservations based on the same "keep everything clear of the speakers" orthodoxy I'd grown up with. But it was clear less than 30 seconds into the audition with the SE-3's "clamped" that it's a technique that worked--and far beyond my expectations.

Even more persuasive, perhaps, were the immediate reactions of, first, my wife (who was blown away by the clearout of audio "mud") and then a "somewhat-audiophile" neighbor who could not get over the "I can almost step into it" soundstage of a well-recorded Gershwin Concerto in F. (Once his wife sees how that effect was achieved I doubt that she'll let him come over to play anymore.)

It is good to see you were willing to try something like clamping your speakers especially if since you are so happy with the results. Both yours and Michaels comments help explain why this may work.

Since my speakers are omnidirectional in the mids and highs it is not something I would try, but I sure like hearing success stories like yours.

Jim

[Michael TubeTrap]

Originally Posted by Still-One

It is good to see you were willing to try something like clamping your speakers especially if since you are so happy with the results. Both yours and Michaels comments help explain why this may work.

Since my speakers are omnidirectional in the mids and highs it is not something I would try, but I sure like hearing success stories like yours.

Jim

Jim,
You break all the rules with your speakers but for everyone else, there is a modification we have found works. Take a look at the Wilson Sasha, where we used short Tubes that stop short before the midrange/tweeter module. On a speaker like this, we do not want to get in the way of the wide dispersion the designer built in. The main thing we are trying to clean up is the lower half of the piano keyboard. Our starting point is somewhere in the middle C to concert A region (250-440Hz) and below, which means we are usually working mostly with the woofer.

Jim's speakers aren't just omni on top, they also have side-firing woofers! We've also had difficulty applying this technique to some studio monitors, too. See what we had to contend when the Di Notte studio in Paris called us with Tannoy Ellipse monitors.

Michael Adams

[tmsorosk]

Jim ... By the amount of sound absorbers you have I assume your system was very bright . Was it ? And did putting that many absorbers in the room take the life out of music . I had to remove about half of my absorbers and place the rest very carefully to get things just right .
Regards Tim

[jimtranr]

Hi, Tim. Though the confluence of tile in the fireplace, glass in the windows and print frames, largely uncovered hardwood flooring, and the hard surfaces of some of the furniture suggest "brightness," system brightness per se was not really a problem (in part because there are also stuffed sofas and a lot of books in the room that ameliorate it), and taming it was not the focus of my trap placement efforts. It would be more accurate to say that my initial efforts were in large part designed to control reflections that tend to smear or obscure tonality and image (while the rear-corner 16" Super Traps were placed there largely to control room modes down to ~40 Hz).

The final setup reflecting Michael's suggested modifications in no way diminishes whatever "life" may exist in a given recording. If anything, it ferrets out, exposes, and focuses in space and time "air," ambience, upper-harmonics, and rhythmic drive previously buried by reflections and other obscuring room artifacts. The result is that you hear more, not less, "life" where its sonic attributes exist within the recording. And because overtones as well as fundamentals are more precisely "delivered" to the listener without reflection-generated time-smear the delineation of, for example, brushes on cymbals or a triangle strike (and its decay) "improves" the perception of the system's upper-mid to high frequency performance without inflicting the sensation of razor-blade brightness on the ear. Think "cleaner," more extended upper frequency response. And spooky "reach-in-and-touch-the-performers" presence with well-executed high-production-value recordings.

[jimtranr]

I thought I'd add a visual to the discussion following the fallout here of Michael's description of the Avalon rollout at the trade show.



Those who've been following this saga and its accompanying photos and diagrams will note that traps no longer adorn the fireplace base. That's because comparative listening tests with familiar program material following the addition of the 11-inch traps to the inboard flanks of the speakers indicate that that addition effectively renders the fireplace traps superfluous--not unlike what occurred with Art Noxon's final three-trap-per-speaker trade show setup.

You'll note that the turntable has shifted leftward in this photo. That allowed me to test placement of a trap atop the fireplace base on dead center of the line running between the speakers. Whether with the diffusor center facing toward the listener or facing the glass doors in front of the fireplace cavity, the audible effect of that placement was virtually nil, suggesting that the addition of the inboard 11-inchers was sufficient to isolate the speakers from the negative reflective effect of the front-wall tile and glass.

"Clamp" placement in this setup is as follows: The front edge of the absorptive center line of the 9-inch traps on either side is flush with the plane of the speaker baffle; the front edge of the center line on the inboard 11-inch trap is set back approximately 1-1/2 inches from the plane formed by the 9-inch front edges and the respective speaker baffle. This is what I started with, and it has given me good audible results. But as indicated by Michael in his post on the subject, I may play a little with that positioning to see if I can get the porridge a little more "just right." If that happens, I'll let you know.